One skilled in the art of fiber extrusion understands that an extruder melts a polymer and a barrel screw forces the melted polymer through a spinneret. The spinneret is similar to a shower head and contains many fine holes. The melted polymer exiting these holes is in the form of molten filaments. These filaments have a diameter. The diameter of the filaments range in size from diameters similar to cotton filaments and increase in size to the diameter of wool. The finer holes produce filaments suitable for apparel and as the holes increase in size the filaments are suitable for carpets and home furnishings such as upholstery, draperies and rugs.
When the polymer used to create these filaments is nylon, the resultant fibers or yarn will be manufactured into textile products that can be dyed using acid dyes and a nylon dye system. The nylon dye system is performed at a temperature range of between 175-200° F. using water as the solvent along with other chemicals known to one skilled in the art of nylon dyeing. It is very desirable and economical to dye at atmospheric pressures.
If the polymers used to create filaments or fibers are polyester (PET) or polypropylene (PP), they will not dye using the nylon dye system.
Polyester is commonly called PET. This is the same material that is readily recycled from discarded plastic beverage bottles. Olefin used in the textile field is usually polypropylene but any olefin polymer can be modified using this invention. The dye system using the present invention is the same as the system used to dye nylon. Anyone skilled in the art of dying nylon will be able to dye the modified yarns and fabrics made using this invention. The nylon dye system is unique because the dye is applied at normal atmospheric pressures. The solvent is water and is effective at temperatures from 175° F. to 212° F. The normal nylon dye cycle is an hour vs. a two to three hour cycle normally required to dye polyester (PET) or cotton. Polypropylene is usually dyed by the pigment dye system which colors the polymer during extrusion. The present invention greatly increases energy savings and increases productivity. Solid shades or multiple tones of a shade are achieved in a single dye bath or print application. Fabrics using the yarns of this invention are manufactured into greige goods produced by the knitting, weaving, tufted or non-woven process. Solid shades are achieved by melt blending a dye enhancing additive (sometimes referred to herein as a “master batch”) into the yarn or fiber and subjecting the fabric to an acid dye bath. The dye enhancing additive used in the process is composed of polymers that are readily available to one skilled in the art of fiber or yarn extrusion. One does not have to be skilled in the art of chemistry to use this invention.
When multiple ends of yarns embodying this invention are used, each can contain differing percentages of dye additives. When the yarns are manufactured into fabrics, the fabric will dye to multiple tones in a single dye bath. By increasing the amount of acid dyeable additive in the polyester (PET) or olefin yarn or fiber, the affinity for acid dye increases accordingly. The fabrics manufactured according to this invention are stored at the dye house undyed. Color is added using conventional nylon acid dye machines or print dye methods. Surprising and novel effects are achieved using economical conventional nylon dye systems known to those skilled in the art. This invention is of particular usefulness in the apparel, carpet and home furnishings industry. The olefin fabrics produced feel and, appear as conventional fabrics but are approximately 30-38% lighter in weight. This is due to the fact that the specific gravity of olefin is 0.91 while the specific gravity of cotton or polyester (PET) is 1.38.